Unless the scripts require parameters or require to be called in a specific order, you should be able to achieve this via a simple loop

#!/bin/bash
for i in $SCRIPT_DIR/fig*-gen.sh
do
./"$i"
done

Caveat:
For this to work, the fig*-gen.sh files should specify the interpreter via the #!/bin/bash line. If they do not, you need to invoke the interpreter explicitly by replacing ./"$i" with something like bash ./"$i"